Concrete conveyer



J. O. BLOMQUIST CONCRETE CONVEYER Filed Nov. 30, 1946 July 4, 1950 Patented July 4, 1950 A UNITED sTATEsPAT-ENT OFFICE;

l CONCRETE CONVEYER Johan Oscar Blomquist, Stockholm, Sweden Application November 30, 1946, Serial No. 713,267 In Sweden December 14, Y1945 In .order to convey ready mixed concrete from the mixer to the working place, i. e. the forms, different manually or automatically operated devices have been used which often have turned out unpractical and impaired by other disadvantages. During the transport and pouring the workable concrete mix should be handled in such 'a way that no separation is caused.

The invention now intends to use a motor driven conveying screw for the concrete, this screw being surrounded by a tube provided with a filling hopper for the concrete mix. Similar arrangements are often used for conveying coal or other solid fuel, the filling hopper then generally at its lower end being formed into a wide container, from which the screw entrains the material through the tube connected with the container. Such a construction of the device is, however, disadvantageous for the purpose in question, as the screw in the container or the lling hopper in this case only would dig a tunnel through the concrete mix,rthe lower part of this tunnel then becoming stii and forming hard walls at the sides of the screw. It has also been shown to be impossible to give the filling hopper adjacent to the screw the same width as the diameter of the tube, which closely surrounds said screw. In such a construction bigger stones would be jammed between the periphery of the screw and the sidewalls of the hopper.

According to the present invention there has now been produced a construction suitable for concrete conveyance, in which the diiculties as mentioned above have been eliminated.

Thus, it is an object of the invention to provide a concrete conveyor, comprising a motor driven screw surrounded by a tubular housing provided with a hopper, the longitudinal side walls of which are continued in ledges inclining towards the horizontal plane and radially directed towards the axis of the screw shaft, said ledges having a width, which is greater than the diameter of the biggest stone portions contained in the concrete mix.

According to another object ofthe invention, a part of the tubular housing is enlarged to form a pressure chamber, disposed in front of the hopper and communicating therewith, said pressure chamber forming an extension of said ledges and extending beyond one or more pitches of the screw thread.

Still other objects of the invention are described with reference to the accompanying drawing, which shows a preferred embodiment of the invention.

2 Claims. (Cl. 1981-164) certain details.

A2 In the drawing: Fig. 1 'shows a longitudinal elevation of. a concrete conveyor. Fig. 2 `shows a cross section through thelling hopper along the line IIe-1I in Fig. 1

Figs. 3 and 4 show suitable constructions of In the figures the worm is designated I, the hopper 2 and the tubular housing 3. As will be seen by Fig. 2 the side 'walls 4 of the hopper `2 are formed in such a way that they formledges 5, inclining to the horizontal and directed radially towards the axis of the screw. Hence, as these ledges always are directedperpendicularly to the periphery of the screw, stones cannot be jammed between the ledges and the screw. Ob` viousl-y,'the ledges must be of such a width that the stones in the mixture cannot be jammed be tween the screw and the 'side walls 4.

The tubular housing 3 is suitably in front of the hopper 2, seen in the feeding direction,"en larged to form a pressure chamber 6 forming an extension of the ledges 5 .and extending beyond one or more pitches of the screw thread. The pressure chamber is provided with a removable cover 1 in order to facilitate cleaning. The'most essential purpose of the pressure chamber, however, is to provide for a possibility of accumulating concrete mix so that the worm will always be well filled in the tubular housing.

As will be seen by Fig. 1 the screw thread is interrupted in a sector 8 disposed in the vertical plane running through the front edge 9 of the pressure chamber. Optionally the screw thread may in this place only be provided with a small gap, which, however, must be of such a dimension that the biggest stones in the concrete mix do not jam between the edges of the pressure chamber and the gap. If there is no pressure chamber, the notch is obviously arranged in the same vertical plane as the front edge of the filling hopper.

The screw thread is at its outer edge bevelled (at I0) backwards, as seen in the feeding direction (see Fig. 3), so that big sand grains occurring in the concrete mix are automatically released during the operation of the conveyor, if they have penetrated between the outer edge of the screw thread and the tubular housing. At its outer and front edge the screw thread can also be provided with a packing strip of rubber, leather or the like, preventing the concrete mix from partly being pressed back between the housing and the screw while pushed forward in the houswards.

ing. This latter arrangement is, however, often not necessary.

So far there has only been described a screw provided with threads. The screw may, however, be provided with wing-shaped portions or the like instead.

When the device as hereinbefore described is used as a concrete conveyor the tubular housing 3 is at its front end generally connected to a conveyor tube l2 of required length, whereby the concrete substance is pressed forward by the pressure of the screw. The whole conveyor assembly with its motor may be placed on a support I3, being tiltably suspended on a shaft I4.

By this arrangement the orifice of the conveying tube I2 can always be directed towards the mouldl ing place when this is moved upwards.

When not operating the conveyor and its appertaining parts should be completely emptied to avoid hardened concrete in the tubes. There may, however, arise some diiculties in evacuating the strongly compressed concrete mix from the long conveying tube I2. This problem has now been solved by arranging a cover at the discharge end of the tube I2 the cover being provided With a compressed air connection. Compressed air is put on simultaneously with the screw being brought into rotation in its opposite direction, i. e. the concrete mass is screwed back- However, it is not suitable to have the compressed air act until complete evacuation, as

i in this Vcase air and concrete would rush out through the hopper. In order to prevent this a hole I5 is arranged at the front end of the housing 3, which hole usually is closed by a screw or the like. Atv the emptying operation the hole is kept open, and when the concrete mass is pressed backwards so far that the air blows through said hole, the ycompressed air may be shut o and the screw alone conveys the remaining concrete back to the hopper.

The concrete conveyor may also be used to watch the consistency of concrete mix. Dependent ony the consistency of the mixture more or ing also being enlarged to form a pressure chamber, disposed in front of the hopper and communicating therewith, said pressure chamber forrming an extension of said ledges and extending beyond one or several pitches of the screw.

2. A concrete conveyor, comprising a motor driven screw surrounded by a tubular housing provided with a hopper, the longitudinal side Walls of which are continued in ledges inclining towards the horizontal plane and radiallyy directed towards the axis of the screw shaft, the housing also being enlarged to form a pressure chamber, disposed in front of the hopper and communieating therewith, said pressure chamber forming an extension of said ledges and extending beyond one or several pitches of the screw, which is Iinterrupted to form a gap substantially in a sector lying in the vertical plane extending through the front edge of the pressure chamber. JOHAN OSCAR BLOMQUIST.

l REFERENCES CITED vThe following references are of record in the 

